General solution of terminal control and observation problems

Mathematical problems of construction of general solutions for terminal control and observation problems are considered. The conditions of existence of a general solution of these problems for linear dynamic systems with a continuous and discrete argument are given. The study was carried out with the support of the Ukrainian Scientific and Technical Center (project No. 545) and the State Fund for Fundamental Research of Ukraine (project No. 1.4/369). Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 80–89, March–April, 2000.     

Models with conjugation conditions and high-accuracy methods of their discretization

New classes of problems with discontinuous solutions are considered. Corresponding generalized problems are obtained. Increased-accuracy computational schemes for their discretization are proposed. Numerical schemes are proposed with asymptotic accuracy not worse than that of similar schemes for problems with smooth solutions. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 110–131, January–February, 2000.     

Parameter Optimization Problems for Multilayer Optical Coatings

Two problems of finding optimal parameters for multilayer optical coatings are considered. They are formulated as multiextremal nonlinear programming problems with a complex objective function. Finding local extrema by first-order methods is discussed. The ways of calculating the gradient of the objective function depending on the number of layers in the optical coating are analyzed. The study was performed within the framework of the Grant of the President of Ukraine for gifted youth, No. 19 (Executive Order of January 12, 2004, No. 6/2004-pr). __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 107–115, July–August 2005.     

基于非交互式Petri网的异步程序验证模型和方法

异步程序使用异步非阻塞调用方式来实现程序的并发, 被广泛应用于并行与分布式系统中. 验证异步程序复杂性很高, 无论是安全性还是活性均达到EXPSPACE难. 提出一个异步程序的程序模型系统, 并在其上定义两个异步程序上的问题: $ \epsilon $等价性问题和$ \epsilon $可达性问题. 通过将3-CNF-SAT规约到这两个问题, 再将其规约至非交互式Petri网的可达性证明两个问题是NP完备的. 案例表明, 这两个问题可以解决异步程序上一系列的程序验证问题.     

Identification of the parameters of a convection diffusion system

Computational algorithms are proposed for the realization of gradient methods based on the solution of direct and conjugate problems in weak formulations for some complex inverse problems of the recovery of parameters of multicomponent parabolic distributed systems. The approach proposed makes it unnecessary to set up Lagrange functionals in explicit form and to use the Green function. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 42–63, January–February 2009.     

Problems of discrete optimization: Challenges and main approaches to solve them

This paper briefly reviews the current state of the art in the field of discrete optimization problems. Emphasis is on the generalization of the experience gained at the V. M. Glushkov Institute of Cybernetics of the National Academy of Sciences of Ukraine in research and development of solution methods and software for various classes of complicated discrete programming problems. The study was partially sponsored by the grant UKM2-2812-KV-06 (SRDF Cooperative Grants Program). __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 3–25, July–August 2006.     

New approaches to robust l2?l∞ and H∞ filtering for uncertain discrete-time systemsfiltering for uncertain discrete-time systems

The problems of robust l ₂−l _∞ and H _∞ filtering for discrete-time systems with parameter uncertainty residing in a polytope are investigated in this paper. The filtering strategies are based on new robust performance criteria derived from a new result of parameter-dependent Lyapunov stability condition, which exhibit less conservativeness than previous results in the quadratic framework. The designed filters guaranteeing a prescribed l ₂−l _∞ or H _∞ noise attenuation level can be obtained from the solution of convex optimization problems, which can be solved via efficient interior point methods. Numerical examples have shown that the filter design procedures proposed in this paper are much less conservative than earlier results.     

Queuing system evolution in a diffusion approximation scheme

An asymptotic diffusion approximation scheme is investigated as applied to the requirement evolution in semi-Markov queuing systems. In proving the diffusion approximation theorem, the compensating operator of the corresponding extended Markov process is used. This problem is solved with the help of a phase merging procedure. Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 136–145, May–June 2009. Original article submitted August 19, 2008.     

State and prospects of development of the national telecommunication network in the spheres of science and education

The project of creating a modern computer network for Ukrainian educational and scientific institutions is considered, and analysis of the stage of development of this network is performed. The objectives and role of telecommunication networks with INTERNET access at the universities and research institutes of the National Academy of Sciences of Ukraine are shown. The resources of the base center and regional centers are analyzed, the topology and data transmission channels of the network are specified, and the prospects of development of the information infrastructure of the educational and scientific spheres are given. Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 3–10, September–October, 1999.     

<Emphasis Type="Italic">HumanPT</Emphasis>: An Open-source,HumanPT Architecture-based,Robotic Application for Low Cost Robotic Tasks

In this paper, first HumanPT architecture for low cost robotic applications is presented. HumanPT architecture differs than other architectures because it is implemented on existing robotic systems (robot  robotic controller) and exploits the minimum communication facilities for real-time control that these systems provide. It is based on well-known communication methods like serial communication (USB, RS232, IEEE-1394) and windows sockets (server–client model) and permits an important number of different type of components like actuators, sensors and particularly vision systems to be connected in a robotic system. The operating system (OS) used is Microsoft Windows, the most widely spread OS. The proposed architecture exploits features of this OS that is not a real-time one, to ensure – in case that the robotic system provide such a facility – control and real time communication with the robotic system controller and to integrate by means of sensors and actuators an important number of robotic tasks and procedures. As implementation of this architecture, HumanPT robotic application and experimental results concerning its performance and its implementation in real tasks are provided. HumanPT robotic application, developed in Visual C++, is an integrated, but simultaneously an open-source software that can be adapted in different types of robotic systems. An important number of robotic tasks or procedures including sensors and particularly vision systems can be generated and executed. Small enterprises by means of the proposed architecture and the open source software can be automated at low cost enhancing in this way their production.     

Logical problems of systems analysis of organization-and-engineering systems and main ways to solve them

Logical problems of systems analysis of organization-and-engineering systems in the modern industry are discussed. The logical foundations of the systems analysis are analyzed. A methodological function of objective structures in a systems analysis of organization-and-engineering systems is found, and a relationship of these structures as results of analysis and synthesis of objectives is established. The main ways to solve logical problems for systems analysis of organization-and-engineering systems that allow solving logical problems are identified. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 140–147, May–June 2006.     

Linear Algebra Considerations for the Multi-Threaded Simulation of Mechanical Systems

A solution method suitable for the multi-threaded simulation ofmechanical systems represented in Cartesian coordinates isproposed and analyzed. In a state-space framework for thesolution of the Differential Algebraic Equations (DAE) ofMultibody Dynamics, the position/velocity stabilization and theacceleration computation are based on iterative solvers applied toequivalent reduced problems. The most in-depth computationalaspect analyzed is the preconditioning, i.e., the direct solutionof the reduced systems. Provided a topology index reduction is first applied to the model, the effort for the direct solution of the reduced systems is shown to be of order O(N _J ), where N _J is the number of joints in the model. The recurring theme of thepaper is the central role that the topology of the mechanicalsystem plays in the overall performance of the numericalsimulation. Based on the topology of the model, parallelcomputational threads can be established to start in the equationformulation and continue through the iterative numericalalgorithms employed for the numerical solution. Task schedulingthese parallel threads is expected to redeem real-time performancefor certain classes of complex applications.     

Hermite WENO Schemes and Their Application as Limiters for Runge-Kutta Discontinuous Galerkin Method,III: Unstructured Meshes

In [J. Comput. Phys. 193:115–135, 2004] and [Comput. Fluids 34:642–663, 2005], Qiu and Shu developed a class of high order weighted essentially non-oscillatory (WENO) schemes based on Hermite polynomials, termed HWENO (Hermite WENO) schemes, for solving nonlinear hyperbolic conservation law systems, and applied them as limiters for the Runge-Kutta discontinuous Galerkin (RKDG) methods on structured meshes. In this continuation paper, we extend the method to solve two dimensional problems on unstructured meshes. The emphasis is again on the application of such HWENO finite volume methodology as limiters for RKDG methods to maintain compactness of RKDG methods. Numerical experiments for two dimensional Burgers’ equation and Euler equations of compressible gas dynamics are presented to show the effectiveness of these methods. The research was partially supported by the European project ADIGMA on the development of innovative solution algorithms for aerodynamic simulations, NSFC grant 10671091 and JSNSF BK2006511.     

Evolutionary Optimization of Machining Processes

Optimization of machining processes plays a key role in meeting the demands for high precision and productivity. The primary challenge for machining process optimization often stems from the fact that the procedure is typically highly constrained and highly non-linear, involving mixed-integer-discrete-continuous design variables. Additionally, machining process models are likely discontinuous, non-explicit, or not analytically differentiable with the design variables. Traditional non-linear optimization techniques are mostly gradient-based, posing many limitations upon application to today’s complex machining models. Genetic Algorithms (GAs) has distinguished itself as a method with the potential for solving highly non-linear, ill-behaved complex machining optimization problems. Unlike traditional optimization techniques, GAs start with a population of different designs and use direct search methods stochastically and deterministically toward optimal and feasible direction. However, GAs still has its own drawbacks when it is applied to machining process optimization, including the lack of efficiency due to its binary representation scheme for continuous design variables, a lack of local fine-tuning capabilities, a lack of a self-adaptation mechanism, and a lack of an effective constraint handling method. A novel and systematic evolutionary algorithm based on GAs is presented in this paper in the areas of problem representation; selection scheme; genetic operators for integer, discrete, and continuous variables; constraint handling method; and population initialization to overcome the underlying drawbacks. The proposed scheme has been applied to two machining problems to demonstrate its superior performance.     

On stability, -gain and control for switched systems

This paper addresses the issues of stability, L₂-gain analysis and H_∞ control for switched systems via multiple Lyapunov function methods. A concept of general Lyapunov-like functions is presented. A necessary and sufficient condition for stability of switched systems is given in terms of multiple generalized Lyapunov-like functions, which enables derivation of improved stability tests, an L₂-gain characterization and a design method for stabilizing switching laws. A solution to the H_∞ control problem for switched systems is also provided.     

Solution of inverse boundary-value problems for multicomponent parabolic distributed systems

Computational algorithms implementing gradient methods based on solution of direct and adjoint problems in weak formulations are proposed for a number of complex-valued inverse problems of parameter renewal in multicomponent parabolic distributed systems. This approach makes it unnecessary to construct Lagrangian functionals explicitly and to use Green’s functions. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 49–73, July–August 2007.     

Sensitivity analysis of coupled structural–acoustic systems subjected to stochastic excitation

A development for computing the acoustic pressure spectral density and its sensitivity of coupled structural–acoustic systems subjected to stochastic excitation is presented. Previous work in the area of structural–acoustic response considered systems subject to deterministic excitations. The response computation depends on the excitation; therefore, new methods are developed to account for stochastic excitation. The structural–acoustic response is calculated using finite element methods and stochastic analysis techniques. An accurate and highly efficient algorithm series for structural stationary random response analysis, pseudo excitation method (PEM) is used. Numerical examples are given to demonstrate the effectiveness of the methods and the program.     

Die shape optimisation for net-shape accuracy in metal forming using direct search and localised response surface methods

In this paper, three direct search algorithms, i.e. a modified simplex, random direction search and enhanced Powell’s methods together with a new localised response surface method are presented and applied to solve die shape optimisation problems for achieving net-shape accuracy in metal forming processes. The main motivation is to develop efficient and easy to implement optimisation algorithms in metal forming simulations which often involve complex tool and workpiece interaction and coupled thermal and mechanical analysis. Three case studies are presented including a simple upsetting, a 2D blade forging and a forward extrusion problem. In all cases, the objective was to achieve net-shape accuracy of the formed parts, one important criterion for precision forming. C+ + programs were developed to implement these algorithms and to automatically integrate optimisation computation and forging simulation. The optimisation results from the three case problems show that direct search based methods especially the modified simplex and the localised response surface methods are computationally efficient and robust for net-shape forging and extrusion optimisation problems. It is also suggested that these methods can be used in more complex forging problems where die shape design and optimisation are essential for achieving net-shape accuracy.     

On solving systems of ordinary differential equations on MIMD-computers

The error of solution of Cauchy problems for systems of ordinary differential equations is estimated in the case where the input data are approximate. It is shown how to prepare a program for computing the right-hand sides of the system automatically and simultaneously. Diagrams are presented to illustrate the efficiency of parallelization. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 175–182, March–April 2007.